package com.cg.leetcode;

import org.junit.Test;

import java.util.HashMap;
import java.util.HashSet;

/**
 * 36.有效的数独
 *
 * @program: LeetCode->LeetCode_36
 * @description: 36.有效的数独
 * @author: cg
 * @create: 2021-08-31 16:12
 **/
public class LeetCode_36 {

    @Test
    public void test36() {
        System.out.println(isValidSudoku(new char[][]{
                {'5', '3', '.', '.', '7', '.', '.', '.', '.'},
                {'6', '.', '.', '1', '9', '5', '.', '.', '.'},
                {'.', '9', '8', '.', '.', '.', '.', '6', '.'},
                {'8', '.', '.', '.', '6', '.', '.', '.', '3'},
                {'4', '.', '.', '8', '.', '3', '.', '.', '1'},
                {'7', '.', '.', '.', '2', '.', '.', '.', '6'},
                {'.', '6', '.', '.', '.', '.', '2', '8', '.'},
                {'.', '.', '.', '4', '1', '9', '.', '.', '5'},
                {'.', '.', '.', '.', '8', '.', '.', '7', '9'}}));
    }

    /**
     * 请你判断一个 9x9 的数独是否有效。只需要 根据以下规则 ，验证已经填入的数字是否有效即可。
     * 数字 1-9 在每一行只能出现一次。
     * 数字 1-9 在每一列只能出现一次。
     * 数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。（请参考示例图）
     * 数独部分空格内已填入了数字，空白格用 '.' 表示。
     * <p>
     * 注意：
     * 1) 一个有效的数独（部分已被填充）不一定是可解的。
     * 2) 只需要根据以上规则，验证已经填入的数字是否有效即可。
     * <p>
     * 示例 1：
     * 输入：board =
     * [["5","3",".",".","7",".",".",".","."]
     * ,["6",".",".","1","9","5",".",".","."]
     * ,[".","9","8",".",".",".",".","6","."]
     * ,["8",".",".",".","6",".",".",".","3"]
     * ,["4",".",".","8",".","3",".",".","1"]
     * ,["7",".",".",".","2",".",".",".","6"]
     * ,[".","6",".",".",".",".","2","8","."]
     * ,[".",".",".","4","1","9",".",".","5"]
     * ,[".",".",".",".","8",".",".","7","9"]]
     * 输出：true
     * <p>
     * 示例 2：
     * 输入：board =
     * [["8","3",".",".","7",".",".",".","."]
     * ,["6",".",".","1","9","5",".",".","."]
     * ,[".","9","8",".",".",".",".","6","."]
     * ,["8",".",".",".","6",".",".",".","3"]
     * ,["4",".",".","8",".","3",".",".","1"]
     * ,["7",".",".",".","2",".",".",".","6"]
     * ,[".","6",".",".",".",".","2","8","."]
     * ,[".",".",".","4","1","9",".",".","5"]
     * ,[".",".",".",".","8",".",".","7","9"]]
     * 输出：false
     * 解释：除了第一行的第一个数字从 5 改为 8 以外，空格内其他数字均与 示例1 相同。 但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。
     * <p>
     * 提示：
     * 1) board.length == 9
     * 2) board[i].length == 9
     * 3) board[i][j] 是一位数字或者 '.'
     *
     * @param board
     * @return
     */
    public boolean isValidSudoku(char[][] board) {
        // 使用Set集合元素不重复的特性解决
        // 行循环
        for (int i = 0; i < 9; i++) {
            HashSet<Character> setLine = new HashSet();
            HashSet<Character> setCol = new HashSet();
            HashSet<Character> setBox = new HashSet();
            // 列循环
            for (int j = 0; j < 9; j++) {
                if (board[i][j] != '.' && !setLine.add(board[i][j])) {
                    return false;
                }
                if (board[j][i] != '.' && !setCol.add(board[j][i])) {
                    return false;
                }
                // 3x3宫格计算
                // 3宫格的行
                int a = (i / 3) * 3 + j / 3;
                // 3宫格的列
                int b = (i % 3) * 3 + j % 3;
                if (board[a][b] != '.' && !setBox.add(board[a][b])) {
                    return false;
                }
            }
        }
        return true;
    }
    /*public boolean isValidSudoku(char[][] board) {
        // 数组解决
        // init data
        HashMap<Integer, Integer>[] rows = new HashMap[9];
        HashMap<Integer, Integer>[] columns = new HashMap[9];
        HashMap<Integer, Integer>[] boxes = new HashMap[9];
        for (int i = 0; i < 9; i++) {
            rows[i] = new HashMap<Integer, Integer>();
            columns[i] = new HashMap<Integer, Integer>();
            boxes[i] = new HashMap<Integer, Integer>();
        }

        // validate a board
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                char num = board[i][j];
                if (num != '.') {
                    int n = (int) num;
                    int boxIndex = (i / 3) * 3 + j / 3;

                    // keep the current cell value
                    rows[i].put(n, rows[i].getOrDefault(n, 0) + 1);
                    columns[j].put(n, columns[j].getOrDefault(n, 0) + 1);
                    boxes[boxIndex].put(n, boxes[boxIndex].getOrDefault(n, 0) + 1);

                    // check if this value has been already seen before
                    if (rows[i].get(n) > 1 || columns[j].get(n) > 1 || boxes[boxIndex].get(n) > 1) {
                        return false;
                    }
                }
            }
        }
        return true;
    }*/

}
